1. Field of the Invention
The present invention relates to a method for manufacturing electronic components including conductive patterns that are laminated to each other with insulating layers provided therebetween, to a mother substrate, and to an electronic component.
2. Description of the Related Art
In FIG. 5A, one example of a coil component is shown by a schematic perspective view. In FIG. 5B, a schematic cross-sectional view of the coil component in FIG. 5a taken along a line A-A is shown (for example, see Patent Document 1). This coil component 30 includes coiled conductive patterns 31 (31A and 31B) that are laminated to each other with an insulating layer 32 provided therebetween.
The coil component 30 is manufactured as described below. As shown in FIG. 6A, a conductive pattern layer is formed which includes the conductive patterns 31 provided at intervals therebetween on the same plane. Conductive pattern layers are laminated to each other with the insulating layer 32 provided therebetween, so that a laminate 33 as shown in FIG. 6b is formed. This laminate 33 is a laminate in which the coil components 30 are collectively formed. After being formed, the laminate 33 is cut along cutting lines L provided along boundaries between the individual coil components 30, so that the coil components 30 are separated from each other. Through the manufacturing process thus described, the coil components 30 are manufactured.
Another example of a related coil conductor is disclosed in Japanese Unexamined Patent Application Publication No. 7-122430 (Patent Document 1).
In the laminate 33 formed in a process for manufacturing the coil components 30, for example, as shown in a schematic cross-sectional view of FIG. 7, a large gap S is formed between adjacent conductive patterns 31 of the coil components 30. Thus, a large amount of an insulating material is provided in the gap S formed between the conductive patterns 31 from the insulating layer 32. Consequently, for example, a problem may arise in that a gap d between the conductive patterns 31A and 31B in the lamination direction is decreased more than that originally designed or in that the gap d between the conductive patterns 31A and 31B varies. Therefore, the electrical properties of the coil component 30 are varied, and as a result, it has been difficult to improve the reliability of the performance of the coil component 30.
Accordingly, a method shown in FIG. 8 has been proposed. According to this proposed method, in order to form a conductive pattern layer of the laminate 33, the electronic component-forming conductive patterns 31 are formed, and in addition, a dummy pattern 35 which is not electrically connected to the conductive patterns 31 is formed along cutting lines. With the formation of the dummy pattern 35 as described above, the amount of a conductive pattern formed in the gap S between adjacent conductive patterns 31 of the coil components 30 is increased. Thus, the amount of the insulating material provided in the gap S from the insulating layer 32 is decreased. As a result, the gap d between the conductive patterns 31A and 31B can be formed substantially as originally designed.
However, for example, with the formation of the dummy pattern 35, the following problems may arise. The purpose of the dummy pattern 35 is to increase the amount of the conductive pattern formed in the gap S between the adjacent conductive patterns 31 of the coil components 30. In view of this purpose, the dummy pattern 35 preferably has a large width. However, when the dummy pattern 35 is formed to have a large width, the following problems may occur. In the case in which the dummy pattern 35 is formed to have a large width, even when the position at which the dummy pattern 35 is to be formed is only slightly shifted, the dummy pattern 35 enters a region in which the electronic component is to be formed from a region which is to be cut and removed when the laminate 33 is processed by cutting. In this case, as shown in a cross-sectional view of FIG. 9B, a portion of the dummy pattern 35 may disadvantageously remain in the coil component 30 which is separated from the laminate 33. In addition, when the dummy pattern 35 is formed to have a large width, when the cutting position is shifted while the laminate 33 is being cut as shown in FIG. 9A, a portion of the dummy pattern 35 is likely to remain in the coil component 30 which is separated from the laminate 33 as shown in a cross-sectional view of FIG. 9B. The cut surface of the dummy pattern 35 is exposed at the side surface of the coil component 30. This remaining dummy pattern 35 causes the following problems.
The coil component 30 separated from the laminate 33 may be processed by plating for surface treatment in some cases, and in this case, plating is disadvantageously and unnecessarily performed onto the exposed portion of the dummy pattern 35. In addition, when a voltage is applied to the dummy pattern 35, and a potential difference is generated between the conductive pattern 31 and the dummy pattern 35, migration occurs between the dummy pattern 35 and the conductive pattern 31, thereby causing a problem of degradation in electrical properties of the coil component 30.
To prevent the problems described above, when the dummy pattern 35 is formed to have a small width, a problem may occur in that delamination (peeling between layers) is generated as described below. That is, when the dummy pattern 35 is formed, a convex portion in conformity with the shape of the dummy pattern 35 is formed at the upper surface of the laminate 33 in a region in which the dummy pattern 35 is formed. In addition, at each of two sides of the convex portion, the insulating layer is provided in a gap between the dummy pattern 35 and the conductive pattern 31 adjacent thereto. As a result, a concave portion is formed. As the width of the dummy pattern 35 is decreased, the gap between the dummy pattern 35 and the conductive pattern 31 adjacent thereto is increased, and the depression of the insulating layer therebetween is increased. Consequently, as shown in a schematic cross-sectional view of FIG. 10, in the laminate 33, the height difference between the top portion of a convex 36 formed in conformity with the dummy pattern 35 and the bottom portion of a concave portion 37 formed at each of the two sides of the convex portion 36 is increased. In addition, when the width of the dummy pattern 35 is decreased, the width of the convex portion 36 is also decreased in conformity with the width of the dummy pattern 35. Thus, in a step of pressing the laminate 33 which is performed before the laminate 33 is separated by cutting, a large pressing force is applied to the thin convex portion 36.
As shown by an arrow F in FIG. 10, the large pressing force applied to this convex portion 36 propagates to the bottom portion (that is, a portion having a small layer thickness) of the concave portion 37. In addition, a convex portion 38 caused by the conductive pattern 31 is also formed at the upper surface of the laminate 33, and in the step of pressing the laminate 33, as shown by an arrow F′ in FIG. 10, a pressing force applied to the convex portion 38 also propagates to the bottom portion of the concave portion 37. As described above, since the forces F and F′ facing each other are applied to the portion having a small layer thickness, an upward force shown by an arrow U in FIG. 10 is generated at the portion having a small layer thickness and a small strength. As a result, delamination (peeling between layers) may occur such that the insulating layer is peeled away from the conductive patterns located thereunder. Accordingly, the electrical properties of the coil component 30 are seriously degraded, and the components may be disadvantageously rejected as defective.